NEW YORK ( MainStreet) — Spending over $600 to borrow something isn't fun. In fact, for many people, it isn't plausible given their budget. But that is the price you may pay if you decide to rent an automobile for a week without the proper money-saving knowledge.

According to IBIS World, the rental car industry rakes in about $31 billion a year and counting. There's no need for you to add to that figure more than you have to, especially if you heed this advice on how you can save on your next car rental:

Go Small

"You can sometimes save a nice chunk of change by renting with a smaller, local agency rather than the big guys," says Robert Firpo-Cappiello, executive editor at Budget Travel . Thanks to trip planning sites such as Priceline and Kayak, minor rental companies, which make up less than 2% of the industry's market share, can be found easily by deal-seekers.

While searching Priceline for an upcoming trip, I found that Avis wanted to charge about $450 for the same economy car that Fox Rental offered for $125, a price almost four times less than the original figure.

Tip: Remember that some travel sites place the most popular (and bigger) renters at the front of search results. For deeper discounts, scroll through further options.

Snag Rewards

Budget Travel says it might pay off to join rental rewards programs, even with smaller companies:

"Members of Payless Perks Club, for example, can save up to 5% on rentals. E-Z Rent-a-Car, which has 36 locations worldwide, gives its program members up to 2 percent off all rentals, and its Facebook fans get 3 percent off on top of that."

See your desired renter's web page for more details.

Think 'Sharing'

The term car sharing "is clearly branding" to "sound smart" suggests Firpo-Cappiello. "But it really amounts to having the option of renting by the minute or by the hour rather than by the day," he says.

Car sharing companies like ZipCar are different from typical renters, in that customers pay for a membership rather than for a specific car. They also rent cars directly from the lot instead of waiting in line. This option is ideal for university students and urbanites that can get by most of the time without a vehicle.

Tip: Beware, if you need a longer car rental, don't go car sharing. Rentals are charged by the hour, and a week could easily run you about $1,000.

Pay Online

If you decide to go with bigger rental companies like Budget and Hertz, there are still ways to save a buck. Paying for your rental immediately with the 'pay now' feature could save you almost 35% on your next rental.